The Once and Future Dream of New York

Unlike ants, moles, gophers and skinks, humans aren’t instinctively tunneling creatures. When we go underground, we are partly admitting that we’ve made a mess on the surface and partly showing off.

In Manhattan, where street traffic tends to stall, only one subway runs the length of the East Side. Every weekday, 1.3 million passengers — more than are carried in 24 hours by the transit systems of Boston, Chicago and San Francisco combined — cram onto the Lexington Avenue line. Yet the chaos above and below has inspired afeat: about 475 laborers are now removing 15 million cubic feet of rock and 6 million cubic feet of soil — more than half an Empire State Building by volume — out from under two miles of metropolis. In December 2016, that tunnel will make its debut as a portion of the Second Avenue subway — the great failed track New York City has been postponing, restarting, debating, financing, definancing and otherwise meaning to get in the ground since 1929.

This past spring, between 69th Street and 72nd Street on Second Avenue, cages descended every eight hours, five days a week, lowering roughly 50 men in neon vests and hard hats into a deep hole. Overhead, fluorescent bulbs provided a noonish light and yellow ventilation tubes undulated. A cool, roaring wind filled the void and carried the intense aroma of Emulex explosives, an ammonialike, Fourth of July smell. Men with tripods surveyed; men with blowtorches welded; men guiding hoses poured concrete (men outnumber women 100 to 1). They took brief lunch breaks and relieved themselves hastily where and when they could.

The hurry actually began more than 80 years ago, when city leaders first proposed constructing a new subway parallel to the Lexington line to serve the developing East Side. It would run from 125th Street south to Houston and cost $86 million. Then came the Great Depression. Then World War II. Then existing subways needed repairs. In the early ’70s, short sections of the Second Avenue tunnel were burrowed at the foot of the Manhattan Bridge, between 99th Street and 105th and between 110th and 120th, before the city’s looming bankruptcy in 1975 halted all digging. The dream of a Second Avenue subway lay dormant until April 12, 2007, when contractors for the Metropolitan Transportation Authority again broke ground — to extend the Q line from 63rd and Lexington over to Second Avenue and up to 96th Street. That alone costs $4.5 billion. Eventually they will lengthen the Q to 125th and dig a new line, the T, from the Financial District straight up Second Avenue to 125th Street. At least that’s the plan.

One evening in March, Amitabha Mukherjee, an engineering manager at Parsons Brinckerhoff, the firm supervising construction at Second Avenue, led a small group through a tunnel headed from 69th Street toward 63rd. The tunnel was dark, but there was, in fact, a light burning at the end. Where the rock was naturally fractured, groundwater squeezed in, darkening the walls with Rorschach figures: here a stegosaurus, there a lady in a gown.

“Geology defines the way you drive the tunnel,” Mukherjee said. The bedrock below Second Avenue and for much of the rest of Manhattan is schist — a hard, gray black rock shot through with sheets of glittery mica. Some 500 million years ago, Manhattan was a continental coastline that collided with a group of volcanic islands known as the Taconic arc. That crash crumpled layers of mud, sand and lava into schist, lending it an inconsistent structure and complicating tunneling: in some places, the schist holds firmly together, creating self-supporting arches; in others, it’s broken and prone to shattering, forcing workers to reinforce the tunnel as they go to keep it from falling.

The first time New York confronted its bedrock to build a subway, in 1900, the method was “cut and cover”: nearly 8,000 laborers given to gambling, fighting and swearing were hired to pickax and dynamite their way through streets and utility lines for two miles. Their efforts were quick — they finished in four years — but their blasts smashed windows and terrorized carriage horses. Tunnels collapsed, killing workers and swallowing storefronts.

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Current technology permits a subtler approach: workers chiseled a launch box at 96th Street and in it assembled a tunnel-boring machine, a mechanical worm with a 130-ton head full of whirling steel discs. The discs chewed two 22-foot-wide tunnels at a depth of 80-feet — enough to slide below water, gas, and electric mains, connect to the station at 63rd and keep the incline of the track always below 3 percent, the steepest grade trains can reliably climb. Beforehand, to test the stability of the ground, engineers took two-inch-wide borings every 1,000 feet, from the street to below the floor of the planned tunnel. In the middle of 92nd, they discovered a challenge: soil and crumbly rock underpinning the city that, if jostled, could cause quaking above. “If we settle the ground in a cornfield it doesn’t really matter,” Mukherjee says. “Here if I settle the ground, I collapse the buildings.” To firm up the site, contractors drilled eight-inch-wide, 80-foot-deep holes and inserted steel pipes. Into those pipes they pumped a constant stream of calcium-chloride brine chilled to minus-13 degrees. In 10 weeks, the earth was frozen solid, and they could cut and brace the tunnel so it would support the surrounding sediment after the ground thawed.

A 7 a.m. shift boss, Ryan McGinty, had recently come up from the cavern and was sitting on a stool at Daisy’s Cafe, near the corner of 72nd and Second one afternoon, still wearing his hard hat when an explosion shook the restaurant. “There you go, that can give you a jump,” he said of an experience local residents have bemoaned for years. To expand a tunnel into a hangar-size station, workers drill holes in the rock, tamp in Emulex with wooden poles, rig detonators and clear out; the ensuing blast advances their cause 8 to 12 feet. After a blast, workers spray water to settle the dust and liquid concrete to reinforce and waterproof the walls. Then they haul up the debris, most of which goes to New Jersey landfills and recycling centers, though some is becoming part of a golf course in the Bronx. During the creation of the 72nd Street station hole, up to three blasts shook the earth every day and roughly 80 trucks carted away 1,600 tons of rubble.

McGinty is a sandhog, one of the New York City miners of Local 147, who got their start planting the caissons for the Brooklyn Bridge nearly 150 years ago. There is still no way to mine a tunnel without sending men into it. Underground, they breathe chemical fumes and dust, no matter how well filtered the air. Water and mud splash up and rain down. They yell themselves hoarse over the rumbling of machines and don’t always wear earplugs against the din. “I think the biggest thing I’m sacrificing is my health,” McGinty said. “But for me to do something I love and be proud of what I do — If I made it to 60, I’d be happy.”

New Yorkers haven’t always been eager to venture below the sidewalk. When Alfred Ely Beach, the publisher of Scientific American, built a blocklong prototype subway in 1870, he dragged chandeliers and a grand piano down to distract riders from fears about hell-demons or vermin. The new Second Avenue stations will appeal to riders with artwork by Chuck Close, Jean Shin and Sarah Sze. By then, commuters will be milling among “so many appurtenances” — mall-style escalators, mezzanines, maps — that “the scale of the actual shell of the structure” will be lost, says Mukherjee, the engineering manager.

But now to visit a raw station is to behold a wonder — to stand inside of a canyon or a glacial crevasse. The president of M.T.A. Capital Construction Company, Michael Horodniceanu, has taken East Siders on Saturday cavern tours, in part to make up for the blasting. “They’re all kind of in awe of what they’re seeing,” he said, “because they understand that it’s been created by men. The question that I always get: ‘What was here before?’ The answer is, ‘Solid rock.’ ”

Richard Barnes is a recipient of a Smithsonian Artist Research Fellowship for 2012.